I was at a presentation a few weeks ago where the speaker went through about 50 data rich slides in about 35 minutes and finally looked up at the audience and announced, "I'll have to go faster if I'm going to get through all my slides." He did and the entire talk was a waste.
Talking faster is not an answer to time constraints. Nor is it essential that you get through every slide. 24 hours after your talk, and if you're good, the audience might remember your overall message and one or two key slides, but not more. Make sure you haven't gone so fast that they don't even recall that.
Prepare for the presentation by having a strategy in mind for dealing with unexpected time problems. You never know if the presentation will start on time, whether audience questions (which you want!) will change the flow, etc. Come prepared with strategies to short-circuit some of the details while allowing the key message to be transmitted.
Speeding up to meet a time constraint is something that seems to give some satisfaction for the speaker, it works against audience needs.
